Polycarbonate surfaces having tenaciously adhered organopolysiloxane coatings thereon and process for making

ABSTRACT

Process, and the article produced thereby, for providing a tenaciously adhered, hard, acetone-resistant and mar-resistant coating on articles having a polycarbonate surface. The process includes priming the polycarbonate surface with preferably gammaaminopropyltriethoxysilane, then coating the primed surface with a solution of a solvent-soluble, further-curable organopolysiloxane in an organic solvent and thereafter evaporating the solvent and finally curing the organopolysiloxane. The solvent-soluble, further-curable organopolysiloxane is produced by heating methyltrialkoxysilane or a mixture of methyltrialkoxysilane and phenyltrialkoxysilane and water in the presence of a hydrolysis catalyst at a sufficient temperature and for a suitable time to form a partial condensation product, concentrating this product by heating to remove some alkanol by-product and water and thereafter precuring the product by heating below the gel point thereof.

United States Patent [4 1 Mar. 21, 1972 Gagnon [54] POLYCARBONATESURFACES HAVING TENACIOUSLY ADHERED ORGANOPOLYSILOXANE COATINGS THEREONAND PROCESS FOR MAKING [72] Inventor: Donald W. Gagnon, 6802 Gaines MillDrive, Sylvania, Ohio 43560 [22] Filed: Apr. 8, 1970 [21] Appl. No.:26,803

[52] US. Cl. ..1l7/72, 117/47 A, 117/1388 F, 1 17/161 ZA [51] Int. Cl...B44d l/092, B32b 27/08 [58] Field ofSearch ..1l7/72, 76 F, 76 T, 138.8E, 117/13.8 A, 138.8 B, 47 A [56] References Cited UNITED STATES PATENTS3,451,838 6/1969 Burzynski et al. ..1l7/138.8 E X 3,498,824 3/1970Chadha "117/72 3,252,278 5/1966 Marzocchi et al. 17/72 X 3,309,2223/1967 Caldwell ....l l7/l38.8 F 3,389,114 6/1968 Burzynski et al.....260/46.5 X 3,389,121 6/1968 Burzynski et al. ..260/46.5

Nugent et al. ..260/46.5 Keil ..1 17/72 Process, and the articleproduced thereby, for providing a tenaciously adhered, hard,acetone-resistant and mar-resistant coating on articles having apolycarbonate surface. The process includes priming the polycarbonatesurface with preferably gamma-aminopropyltriethoxysilane, then coatingthe primed surface with a solution of a solvent-soluble, further-curableorganopolysiloxane in an organic solvent and thereafter evaporating thesolvent and finally curing the organopolysiloxane. The solvent-soluble,further-curable organopolysiloxane is produced by heatingmethyltrialkoxysilane or a mixture of methyltrialkoxysilane andphenyltrialkoxysilane and water in the presence of a hydrolysis catalystat a sufficient temperature and for a suitable time to form a partialcondensation product, concentrating this product by heating to removesome alkanol by-product and water and thereafter precuring the productby heating below the gel point thereof.

ABSTRACT 14 Claims, No Drawings POLYCARBONATE SURFACES HAVINGTENACIOUSLY ADI-IERED ORGANOPOLYSILOXANE COATINGS THEREON AND PROCESSFOR MAKING This invention generally relates to coatings forpolycarbonate surfaces; more particularly it relates toorganopolysiloxane coatings for polycarbonates and still moreparticularly it relates to a technique for providing uniformly andtenaciously adhered organopolysiloxane coatings on solid polycarbonatesurfaces. I

Polycarbonate resins, and substrates produced therefrom, are known topossess certain desirable properties which have been responsible fortheir use in various industries. The resins are typically transparent,noncorrosive, nontoxic, stain resistant, self-extinguishing, have lowwater absorption, fair impact strength, fair heat resistance, fairdimensional stability and desirable electrical properties. These resinshave therefore been advantageously used as cable wrappings, slot liners,magnetic recording tape, sterilizable packages, lenses, viewingclosures, for example, face plates, window applications and Windshields,honeycomb cores and safety laminates. Unfortunately, however, because ofcertain detrimental characteristic properties of the polycarbonates,these resins have not achieved their full potential. The polycarbonates,for example, are known to possess a relatively soft surface and areconsequently highly susceptible to marring and scratching, which, ofcourse, is not acceptable if the ultimate use is as a windshield, faceplate or the like.

In order to increase the utility of polycarbonates, coatings have beenapplied thereon. For example, in US. Pat. No. 3,451,838organopolysiloxane coatings are applied onto polycarbonate surfaces,which coatings have many desirable properties, for example, they areclear, glossy, hard, mar-resistant, scratch-resistant. These coatingsalso exhibit excellent resistance to attack by polar organic solvents,for example, the ketones and especially acetone. Unfortunately, theseorganopolysiloxane coatings, though possessing many desirable propertiesdo not possess the desired degree of adherence to the polycarbonateresins. Thus, the organopolysiloxane coated polycarbonates would yetreceive more use in the art if a technique could be devised for moretenaciously bonding the organopolysiloxane to the polycarbonate surface.This is especially true when the polycarbonates are intended for use asviewing closures, for example as a windshield or face plate.

With the foregoing in mind it is an object ofthis invention to producetenaciously adhered organopolysiloxane coatings on polycarbonatesurfaces.

Yet another object of this invention is to provide a method forincreasing the adhesive bond of an organopolysiloxane to a polycarbonatesubstrate.

Yet another object of this invention is to tenaciously bond a thermosetorganopolysiloxane onto a polycarbonate surface.

Still another object of this invention is to provide a tenaciouslyadhered hard, solvent-resistant, scratch-resistant, marresistantorganopolysiloxane coating onto articles having a polycarbonate surface.

A still further object of this invention is to provide fororganopolysiloxane coatings which are uniformly and tenaciously bondedto a polycarbonate surface.

According to one aspect of this invention, prior to the application ofan organopolysiloxane to polycarbonate surface, the surface is primed bythe application of a compound of the formula H NR -Si(OR) wherein R isan alkylene group of two carbon atoms or three carbon atoms, e.g.,ethylene CH CH and propylene (CH CH CI-I 2) and wherein (OR) is analkoxy group of from one to four carbon atoms, e.g., methoxy,isopropoxy, n-butoxy and the like. The priming may be done in any knownmanner for example by ap plying a solvent solution of H NR Si(OR)compound and then allowing the solvent to evaporate. Suitable solventsinclude water, lower aliphatic alcohols like the C -C alcohols(methanol, butanol, isopropanol, n-pentanol are suitable), and aromaticsolvents including benzene, toluene and the like.

According to a highly preferred aspect of this invention, a

' polycarbonate surface is primed with agamma-aminopropyltrialkoxysilane generally represented by the structuralformula NH -(C H )Si(OR) wherein (OR) is an alkoxy group which includesone to about four carbon atoms such as for example methoxy, ethoxy,isopropoxy, butoxy and the like, R obviously being a C to C alkyl. Mostadvantageously the primer which is employed isgamma-aminopropyltriethoxysilane. The gamma-aminopropyltrialkoxysilanewill advantageously be applied to the polycarbonate surface in a solventsolution by any conventional technique, for example spraying or dipcoating. After the solvent solution application, the primedpolycarbonate surface is allowed to set for a period of time, forexample 15 minutes to about an hour, to allow the solvent to evaporateand thereby deposit a film of the gammaaminopropyltrialkoxysilane on thepolycarbonate surface. Many solvents may be used to apply the primersilanes for example water, aromatic solvents, like benzene, toluene andlower aliphatic alcohols, like the C -C alcohols, or mixtures thereof.Methanol, butanol, isopropanol, ethanol and normal pentanol are quitesatisfactory. The concentration of the gamma-aminopropyltrialkoxysilanepriming solution is generally governed by economic considerations.Concentrations in the range of approximately 0.05% to 5% or 10%, or evenhigher, by weight gamma-aminopropyltrialkoxysilane have proved to bequite satisfactory. It will, of course, be understood that the lowerconcentration limit is generally based on the consideration that asufficient thickness of the gammaaminopropyltrialkoxysilane must bedeposited on the polycarbonate surface to provide for the primingaction; this in general only requires a thickness of approximately 1micron or even less. The upper concentration limit, of course, is simplygoverned by economic considerations. After the polycarbonate surface hasbeen primed with gamma-aminopropyltrialkoxysilane the primed surface iscoated with a solvent solution of a solventsoluble, further-curableorganopolysiloxane, the solvent for the organopolysiloxane is thenevaporated after which time the organopolysiloxane is finally cured to athermoset state to provide a tenaciously adhered, hard,solvent-resistant, scratch-resistant, mar-resistant coating on thepolycarbonate surface.

Advantageously, the solvent-soluble, further-curable organopolysiloxanewhich is employed in a hydrolysis and condensation product ofmethyltrialkoxysilane, wherein the alkoxy group contains from one tofive carbon atoms, like methoxy, isopropoxy, and pentoxy. Thissolvent-soluble, further-curable organopolysiloxane is prepared by aprocess wherein methyltrialkoxysilane is hydrolyzed with water (at leastabout 1.5 moles of water per mole of silane) in the presence of ahydrolysis catalyst, e.g., HCL, for about 1 to 10 hours at a temperaturegenerally between about 40 C. and reflux temperature, preferably withinthe temperature range of about 50 to C. to produce a partialcondensation product; the partial condensation product is thenconcentrated by heating to about 65 to 300 C. and preferably within thetemperature range of about 70 to C. to remove some alkanol byproduct andwater; the concentrated product is then precured at a temperature ofabout 70 to 300 C. and below the gel point thereof and then solidifiedto provide a solid solvent-soluble, further-curable organopolysiloxane.The solid solvent-soluble, further-curable organopolysiloxane is thendissolved, for example to a concentration of about 5 to 85 percent byweight, in a suitable solvent and the solution then applied to theprimed polycarbonate surface, after which the solvent is evaporated andthe organopolysiloxane finally cured to provide a glossy, tenaciouslyadhered, hard, solventresistant, mar-resistant, scratch-resistantthermoset coating on the polycarbonate surface. The solidificationreferred to above may comprise cooling or may include the flaking orspray drying techniques respectively disclosed in US. Pat. Nos.3,414,540 and 3,383,773. Optionally, instead of solidifying the precuredorganopolysiloxane to provide a solid, sol vent-soluble, further-curableorganopolysiloxane, the solidification may be omitted and the precuredorganopolysiloxane dissolved in a suitable solvent and then applied tothe primed polycarbonate surface.

Another solvent-soluble, further-curable organopolysiloxane which isadvantageously applied to the primed polycarbonate surface is thehydrolysis and condensation product ofa mixture of methyltrialkoxysilaneand phenyltrialkoxysilane wherein the alkoxy group contains one to fivecarbons, like methoxy, propoxy, n-pentoxy, etc. This organopolysiloxaneis prepared by a process wherein a mixture of methyltrialkoxysilane andphenyltrialkoxysilane is hydrolyzed with water (at least about 1.5 moleswater per mole of total silane) in the presence of a hydrolysiscatalyst, e.g., HCL., for about 1 to 10 hours at a temperature betweenambient and reflux to produce a partial condensation product, thepartial condensation product is then concentrated by heating to removeabout 50 to 90 mole percent alkanol byproduct in some water; theconcentrated product is then precured at a temperature of about 70 to400 C., usually less than about 250 C., and below the gel point thereofand then solidified to provide a solid, solvent-soluble, further-curableorganopolysiloxane. The solid, solvent-soluble, further-curableorganopolysiloxane is then dissolved, for example to a concentration ofabout to 85 percent by weight, in a suitable solvent and the solutionthen applied to the primed polycarbonate surface after which time thesolvent is evaporated and the further-curable, solvent-solubleorganopolysiloxane finally cured to provide a tenaciously adhered, hard,scratch-resistant, mar-resistant, solvent-resistant, glossy, thermosetcoating on the polycarbonate surface. As indicated above, thesolidification may comprise cooling or include the flaking or spraydrying techniques respectively disclosed in U.S. Pat. Nos. 3,414,540 and3.383,?73. Additionally, as indicated above, instead of solidifying theprecured, further-curable, solvent-soluble organopolysiloxane theprecured product may be dissolved in a suitable solvent and then appliedto the primed polycarbonate surface.

Particularly suitable silanes which are employed to produce thesolvent-soluble, further-curable organopolysiloxanes discussed above aremethyltriethoxysolane and a mixture of methyltriethoxysilane andphenyltriethoxysilane. For further details regarding the preparation ofthe solvent-soluble, further-curable organopolysiloxanes which areadvantageously employed in producing polycarbonate coated articlesreference may be had to U.S. Pat. Nos. 3,389,114 and 3,389,121 both ofwhich are hereby incorporated by reference. Additionally, U.S. Pat. Nos.3,383,773 and 3,414,540 relating to the preparation of the solidsolvent-soluble, further-curable organopolysiloxanes are also herebyincorporated by reference.

in passing, it should be mentioned that the solution of thefurther-curable, solvent-soluble organopolysiloxane may include suitableadjuvants such as fillers, colorants and dopants. in certain instances,it may be desirable to include in the solution about 1 to about 5percent by weight (of the organopolysiloxane solids) of an ultravioletlight absorbing compound like 2-hydroxy-4-methoxybenzophenone or 2,2-dihydroxy-4-methoxybenzophenone. Organic acids such as tartaric,gluconic or citric acid may also be incorporated in theorganopolysiloxane to increase the weather resistance and alter theflexibility of the resulting thermoset organopolysiloxane; in thisregard reference may be had to U.S. Pat. No. 3,457,221. Additionally,the organopolysiloxane which is applied to the primed polycarbonatesurface may be modified by a polyamide which is an alkoxyalkyl-substituted condensation polymer in which alkoxymethyl groupsreplace the amide hydrogen in the polyamide chain; these compositionswill have outstanding flexural properties and are disclosed in US. Pat.Nov 3,457,323.

The polycarbonate surfaces which are advantageously primed and coated inaccordance with this invention are the well-known solid polycarbonates.They are described, for example in the Kirk-Othmer Encyclopedia ofChemical Technology, Second Edition, Vol. 16 at pages 1061 16 and areadditionally discussed in the Encyclopedia of Polymer Science andTechnology, Vol. at pages 710764, (Copyright in 1969 John Wiley andSons, Inc.). Most advantageously the solid polycarbonates which areemployed in accordance with this invention are of the polyaryl carbonatetype having a number average molecular weight of about 16,000 to about24,000 or higher. This type of polycarbonate is represented by thefollowing structural formula I, Q 0 l .n

wherein n is an integer in the range of about 60 to about 90. Thesepolycarbonates are commercially available and one such suitablepolycarbonate is that commercially supplied under the trademark Lexan.

In passing, it should be mentioned that the polycarbonates have alsobeen primed by using a conventional flame treating technique or aconventional acid etching technique. These two types of primingtechniques are not entirely satisfactory, however, in that they producespotty results. That is, the adhesion is not uniform in that in certainareas the organopolysiloxanes will be found to be more strongly bondedthan in other areas. Presumably, this is the result of a nonuniformpriming of the surface. By priming the polycarbonates as contemplated inthis invention it will be found however, that a much more uniform,tenacious bond of the organopolysiloxane to the polycarbonate substratewill be produced. It is worth mentioning that the primers employed inthis invention to produce uniform, tenaciously coated polycarbonatesurfaces, do not produce this outstanding priming effect on allpolymers; for example this priming effect is not realized when the sameprimers are used to prime solid acrylic surfaces.

The following examples are illustrative of the manner practicing thisinvention, it, of course, being understood that the examples are not tobe construed as limiting the invention but merely set forth theexemplary manner of using this invention.

EXAMPLE l-A A solvent-soluble, further-curable organopolysiloxaneprepolymer product was prepared by hydrolyzing and condensing about 1mole of methyltriethoxysilane with about 2 k moles of water and about 3weight parts of HCl per million parts of water and silane, the silanefirst being purified by distillation to about zero parts per million ofHC L.

The reaction mixture was heated with agitation in a flask equipped witha condenser until the pot temperature reached about C. This temperaturewas maintained for about 4 hours. After about 20 minutes, the two phasereaction mixture clarified to a one phase system due to the ethanolliberated in the reaction acting as a mutual solvent. At the end of the4 hour period approximately 78 grams of an ethanol-water mixture (about92 percent alcohol) was removed by distillation. The hydrolysis andcondensation reaction, and concentration thereafter, produced a viscousliquid. The viscous liquid prepolymer was refluxed at 50 percent solidsfor 20 hours to increase the viscosity to 30 centipoises at 50 percentsolids at 20 C. in ethanol.

The viscous liquid having a viscosity of about 30 centipoises at 50percent solids at 25 C. in ethanol was further treated and precured byforming a film thereof and heating the film in a wiped film evaporator.The evaporator was operated at a wall temperature of about 200 C. whichprovides a product temperature of about C. The main residence time inthe evaporator was about 20 seconds. The resultant liquid precuredmaterial was solidified in about 1 to 1 V2 minutes and broken up intoflakes by a drum flaker unit. These flakes of the solvent-soluble,further-curable organopolysiloxane were then dissolved in normal-butanolto a resin solid concentration of about 40 percent by weight. Theresultant solution was then filtered to remove possible contaminantssuch as dust, and dirt.

EXAMPLE l-B A priming solution of gamma-aminopropyltriethoxysilane wasprepared to a concentration of about 1 percent by weight of the silanein normal-butanol. Into this solution there was then dipped a clear,generally rigid polycarbonate substrate having a thickness of aboutone-eighth inch and characterized by the repeating structural unit I"OH; Ol L (13H: .L

This type of polycarbonate is commercially available and supplied underthe trademark Lexan. The polycarbonate substrate was then removed fromthe gamma-aminopropyltriethoxysilane solution and was allowed to remainin the open air for about 45 minutes during which time thenormal-butanol solvent evaporated and thereby deposited a thin film of agamma-aminopropyltrietlioxysilane on the polycarbonate substrate.

The gamma-aminopropyltriethoxysilane primed polycarbonate substrate wasthen dipped into the 40 percent organopolysiloxane solution as preparedin I-A above. While dipping constitutes one mode of coating thesubstrate it, of course, will be apparent that other conventionalcoating techniques such as, for example spray, roller or flow coatingtechniques may also be employed. The gamma-aminopropyltriethoxysilaneprimed polycarbonate substrate, which had now been dip coated as above,was allowed to remain in the open air for a sufficient time to allow thesolvent to evaporate and the resulting organopolysiloxane coating wasthen cured to a thermoset condition by heating at 270 F. for about 30minutes in a forced air circulating oven. The resulting thermosetorganopolysiloxane coating had a thickness of about one-half tothree-fourths mils. Another similarly coated polycarbonate substrate wascured for hours at 200 F. and produced a coating have approximately thesame thickness as referred to above. Both coated substrates were testedin the manner hereinafter to be described and produced equivalentresults.

The polycarbonate substrates which now possess a clear, glossy,thermoset organopolysiloxane coating thereon were then tested todetermine the adhesion, acetone resistance, and hardness of the coatedsurface.

The acetone resistance was determined by wiping the coated surface witha tissue which had been saturated with acetone and then visuallyobserving the coated surface after it had dried. If the coating becomescloudy the acetone resistance is generally designated as poor whereas ifthere is not deterioration in the coatings appearance an excellentdesignation is employed. The polycarbonate substrates having the clear,glossy, cured organopolysiloxane resin coating showed excellent acetoneresistance. That is, the clear coating showed no signs of cloudinessafter the acetone wiping.

The adhesion of the coating is determined by scribing an X in the coatedsurface and then applying adhesive tape to the scribed section. Uponpulling of the tape, if there is no noticeable removal of the coating,it is designated excellent. No coating removal was discernible when theprimed coated substrates of this example were so tested. In contrast,when a similar polycarbonate substrate is coated without employing thegamma-aminopropyltriethoxysilane primer substantial portions of theresulting thermoset organopolysiloxane coating are removed whenemploying this same test procedure.

The hardness of the polycarbonate coated substrates was then determinedby a so-called pencil-hardness test. According to this test two stepsare involved. First of all, the fingernail is firmly translated alongthe coating and if the coating mars the test is discontinued and thecoating is deemed to have poor hardness. lf, on the other hand, nomarring is produced graphite pencils of increasing hardness aresuccessively drawn across the coated surface until a noticeable scribingor surface penetration appears. The pencil, or graphite hardnessproducing the scribe thus becomes the coating hardness designation. Thecoatings as produced hereinbefore have a hardness of approximately 7Hwhich is considered excellent.

ln passing, it should bementioned that the curing of theorganopolysiloxane was observed to require slightly less time than isnormally encountered when a gamma-aminopropyltrialkoxysilane primer isnot employed. That is, it appears that in spite of the fact that thegamma-aminopropyltriethoxysilane was deposited as a film on thepolycarbonate substrate nonetheless a slight catalytic curing effect wasobserved.

EXAMPLE ll The procedure as set forth in Example l-A and 1-8 wasgenerally repeated with the exception that instead of employing afurther-curable, solvent-soluble organopolysiloxane which had beenmanufactured from a methyltriethoxysilane precursor the further-curable,solvent-soluble organopolysiloxane employed in this example was theprepolymer prepared from a mixture of methyltriethoxysilane andphenyltriethoxysilane. In general, the results as set forth in Examplel-B were identical employing the methyltriethoxysilane andphenyltriethoxysilane precursors.

The specific further-curable, solvent-soluble organopolysiloxaneprepolymer was prepared from methyltriethoxysilane andphenyltriethoxysilane using two moles of the methyl precursor silane andone mole of the phenyl precursor silane. The mixture of methyl andphenyltriethoxysilanes was hydrolyzed and condensed with 9 moles ofwater (3 moles of water/mole of total silane) and about 2.5 parts of HClper million parts of water and silane, the silanes first being purifiedby distillation to about 0 parts per million HCl.

The reaction mixture was heated with agitation in a flask equipped witha condenser until the pot temperature reached about C. This temperaturewas maintained for 4 hours. After about 20 minutes, the two phasereaction mixture clarified to a one phase system due to the ethanolliberated in the reaction acting as a mutual solvent. At the end of the4 hour period, approximately 282 grams of an ethanol-water mixture(about 92 percent alcohol) was removed by distillation. The hydrolysisand condensation reaction and the concentration by removal of alkanolbyproduct and water thereafter produced a viscous liquid. The viscousliquid, having a viscosity of about 40 centipoises and 60 percent solidsat 25 C. in ethanol was refluxed for 15 hours to provide the same with aheat history and a final viscosity of about 60 centipoises at 60 percentsolids at 25 C.

The liquid was then precured in a wiped film evaporator operating atabout l95200 C. wall temperature to provide a liquid product temperatureof about l70-l75 C. for mean residence time of less than 40 seconds,namely about 20 seconds. The resultant precured material was chilled andsolidified in about 60 seconds by passing the liquid through a drumflaker. The liquid was solidified into sheets which were broken up intoflakes which had a melting point of about 55 C. and were substantiallyfree from gel. These flakes were then employed in the manner set forthin Example l-A and 1-H and the same results were obtained. That is, theresulting coatings on the primed polycarbonate surface showed excellenthardness, acetone resistance and adhesion.

While the above examples set forth the best mode contemplated inpracticing this invention it will, of course, be apparent thatmodification is possible. For example, while normal-butanol was used asthe solvent for the solvent-soluble, further-curable organopolysiloxaneit will be apparent that other solvents may likewise be employed. Forexample, acetone, methylisobutylketone, methanol, ethanol, isobutanol,ethylacetate, dioxane, ethyleneglycolmonomethylether,ethyleneglycolmonoethylether, ethyleneglycolmonobutylether, and the likemay also be employed.

In general, the final cure of the further-curable, solventsolubleorganopolysiloxane will be effected by heating to a temperature of about100 to about 135 C. for a period of time of between 'r hour to about 24hours. The time and temperature, of course, may be varied in otherranges so long as the polycarbonate substrate which is employed iscapable of withstanding the specific heating intensity employed. Thatis, the curing is done under conditions of time and temperature whichwill not cause any degradation in the properties of the polycarbonatesubstrate. Additionally, if desired, the organopolysiloxanes may becatalyzed by the addition ofa suitable catalyst thereto. In this regard,not only does gammaaminopropyltrialkoxysilanes function as excellentprimers for a polycarbonate surface but these same materials may beadded to the solvent-so1uble, further-curable organopolysilox- I anes tocatalyze the curing rate.

While the invention has been described above with particularity, itwill, of course, be apparent that modifications may be made whichpursuant to the patent statutes and laws do not depart from the spiritand scope of the invention. Accordingly, the scope of the invention isas defined in the following claims.

lclaim:

1. A process for producing an article having a polycarbonate surfacewhich is coated to provide a uniformly and tenaciously adhered, hard,mar-resistant, scratch-resistant, heat-resistant and acetone-resistantcoated surface, the process comprising the steps of:

A. priming said polycarbonate surface with a compound of the formula HNR,Si-(OR) wherein R is an alkylene group of two or three carbon atomsand R is an alkyl group containing between one and four carbon atoms,

B. applying a solution of a solvent-soluble, further-curableorganopolysiloxane in an organic solvent on the primed polycarbonatesurface, said further-curable organopolysiloxane being a precuredhydrolysis and condensation product of a silane of the group consistingof methyltrialkoxysilane and a mixture of methyltrialkoxysilane andphenyltrialkoxysilane in which the alkoxy group contains from one tofive carbon atoms, said organopolysiloxane being prepared by heatingsaid silane and water in the presence of a hydrolysis catalyst for about1 to about 10 hours at a temperature between about 40 C. and reflux toproduce a siloxane partial condensation product, concentrating saidsiloxane partial condensation product by heating to remove about 50 to90 mole percent alkanol byproduct and some water, and precuring theconcentrated product by heating below the gel point thereof to providesaid solvent-soluble, furthercurable organopolysiloxane, and

C. evaporating the solvent for said organopolysiloxane and finallycuring said organopolysiloxane to provide a thermoset coating on saidpolycarbonate surface.

2. The process ofclaim 1 wherein said compound ofthe formula H N-R-Si-(OR) is gamma-aminopropyltrialkoxysilane, wherein said alkoxy groupcontains from one to four carbon atoms.

3. The process as defined in claim 2 wherein saidgammaaminopropyltrialkoxysilane is gamma-aminopropyltriethoxysilane.

4. The process as defined in claim 3 wherein the alkoxy groups of saidmethyltrialkoxysilane and said phenyltrialkoxysilane are ethoxy groups.

5. The process as defined in claim 2 wherein said solventsoluble,further-curable organopolysiloxane is a hydrolysis and condensationproduct of methyltriethoxysilane.

6. The process as defined in claim 2 wherein said solventsoluble,further-curable organopolysiloxane is a hydrolysis and condensationproduct of a mixture of methyltriethoxysilane and phenyltriethoxysilane.

7. The process of claim 2 wherein said polycarbonate is characterized bya reoccurrence of the following structural unit:

8. The article produced by the process of claim 1.

9. A process for producing an article having a solid polycarbonatesurface which is coated to provide a uniformly and tenaciously adhered,hard, mar-resistant, heat-resistant and acetone-resistant coatedsurface, the process comprising the steps of:

A. priming said surface with gamma-aminopropyltriethoxysilane,

B. applying a solution of a solvent-soluble, further-curableorganopolysiloxane in an organic solvent on the primed polycarbonatesurface, said further-curable, solvent-soluble organopolysiloxane beinga precured hydrolysis and condensation product of methyltrialkoxysilanein which the alkoxy group contains between one and five carbon atoms andbeing prepared by heating said silane and water in the presence of ahydrolysis catalyst for about 1 to 10 hours at a temperature betweenabout 40 C. and reflux to produce a siloxane partial condensationproduct, concentrating said partial condensation product by heating to atemperature within the range of about 65 to 300 C. to remove alkanolbyproduct and some water, precuring the concentrated product by heatingat a temperature of between about 70 to 300 C. and below the gel pointthereof to provide said solvent-soluble, further, curableorganopolysiloxane, and

C. evaporating the solvent for said organopolysiloxane and finallycuring said organopolysiloxane to provide a thermoset coating on saidpolycarbonate surface.

10. The process as defined in claim 9 wherein step A comprises the stepof applying a solution of gamma-aminopropyltriethoxysilane onto saidpolycarbonate surface, and allowing the solvent of said solution toevaporate.

11. The process as defined in claim 10 wherein saidmethyltrialkoxysilane is methyltriethoxysilane.

12. A process for producing an article having a polycarbonate surfacewhich is coated to provide a hard, mar-resistant, tenaciously anduniformly adhered, heat-resistant and acetone-resistant coated surface,said process comprising the steps of:

A. priming said polycarbonate surface withgammaaminopropyltriethoxysilane,

B. applying a solution of a solvent-soluble, further-curableorganopolysiloxane in an organic solvent on the primed polycarbonatesurface, said further-curable organopolysiloxane being a precuredhydrolysis and condensation product of a mixture ofmethyltrialkoxysilane and phenyltrialkoxysilane in which the alkoxygroups contain between one and five carbon atoms, saidorganopolysiloxane being prepared by heating said silane and water inthe presence of a hydrolysis catalyst for about 1 to about 10 hours at atemperature between ambient and reflux to produce a siloxane partialcondensation product, concentrating the partial condensation product byheating to remove about 50 to mole percent alkanol byproduct and somewater, precuring the concentrated product at a temperature between about70 and 250 C. and below the gel point thereof to provide saidsolvent-soluble, further-curable organopolysiloxane, and

C. evaporating the solvent for said organopolysiloxane and finallycuring said organopolysiloxane to provide a thermoset coating on saidpolycarbonate surface.

13. The process as defined in claim 12 wherein step A comprises forminga film of gamma-aminopropyltriethoxysilane on said polycarbonatesurface.

14. The process as defined in claim 13 wherein said solventsoluble,further-curable organopolysiloxane is a hydrolysis and condensationproduct of a mixture of methyltriethoxysilane and phenyltriethoxysilane.

P0-1050 UNITED STATES PATENT OFFICE CERTIFlCATE OF CORRECTION Patent No5 ,650,808 Dated March 21, 1972 lnventofls) Donald W. Gagnon It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

' v Column 1, line 65,

should be CH -CH and propylene (-CH -CH -CH and Column 2, line #2, inshould be is Column 2 line #9, after"e.g.," the formulav "HCL should beHCl Column 5, line 10, after "e.g. the formula HCL" should be HCl Column5, line 58, "methyltriethoxysolane" should be me'thyltriethoxysilaneColumn 4, line &7, "HCL" should. be HCl Column 4 line 67, "main" shouldbe mean Column 5 line 55, "not" should be no Column 7, line before "90"insert about Signed and sealed this 15th day of August 1972.

(SEAL) Attestz EDWARD M.PLETCHER,JR. ROBERT GOTTSCHALK Attesting OfficerCommissioner of Patents

2. The process of claim 1 wherein said compound of the formula H2N-R1-Si-(OR)3 is gamma-aminopropyltrialkoxysilane, wherein said alkoxy group contains from one to four carbon atoms.
 3. The process as defined in claim 2 wherein said gamma-aminopropyltrialkoxysilane is gamma-aminopropyltriethoxysilane.
 4. The process as defined in claim 3 wherein the alkoxy groups of said methyltrialkoxysilane and said phenyltrialkoxysilane are ethoxy groups.
 5. The process as defined in claim 2 wherein said solvent-soluble, further-curable organopolysiloxane is a hydrolysis and condensation product of methyltriethoxysilane.
 6. The process as defined in claim 2 wherein said solvent-soluble, further-curable organopolysiloxane is a hydrolysis and condensation product of a mixture of methyltriethoxysilane and phenyltriethoxysilane.
 7. The process of claim 2 wherein said polycarbonate is characterized by a reoccurrence of the following structural unit:
 8. The article produced by the process of claim
 1. 9. A process for producing an article having a solid polycarbonate surface which is coated to provide a uniformly and tenaciously adhered, hard, mar-resistant, heat-resistant and acetone-resistant coated surface, the process comprising the steps of: A. priming said surface with gamma-aminopropyltriethoxysilane, B. applying a solution of a solvent-soluble, further-curable organopolysiloxane in an organic solvent on the primed polycarbonate surface, said further-curable, solvent-soluble organopolysiloxane being a precured hydrolysis and condensation product of methyltrialkoxysilane in which the alkoxy group contains between one and five carbon atoms and being prepared by heating said silane and water in the presence of a hydrolysis catalyst for about 1 to 10 hours at a temPerature between about 40* C. and reflux to produce a siloxane partial condensation product, concentrating said partial condensation product by heating to a temperature within the range of about 65* to 300* C. to remove alkanol byproduct and some water, precuring the concentrated product by heating at a temperature of between about 70* to 300* C. and below the gel point thereof to provide said solvent-soluble, further, curable organopolysiloxane, and C. evaporating the solvent for said organopolysiloxane and finally curing said organopolysiloxane to provide a thermoset coating on said polycarbonate surface.
 10. The process as defined in claim 9 wherein step A comprises the step of applying a solution of gamma-aminopropyltriethoxysilane onto said polycarbonate surface, and allowing the solvent of said solution to evaporate.
 11. The process as defined in claim 10 wherein said methyltrialkoxysilane is methyltriethoxysilane.
 12. A process for producing an article having a polycarbonate surface which is coated to provide a hard, mar-resistant, tenaciously and uniformly adhered, heat-resistant and acetone-resistant coated surface, said process comprising the steps of: A. priming said polycarbonate surface with gamma-aminopropyltriethoxysilane, B. applying a solution of a solvent-soluble, further-curable organopolysiloxane in an organic solvent on the primed polycarbonate surface, said further-curable organopolysiloxane being a precured hydrolysis and condensation product of a mixture of methyltrialkoxysilane and phenyltrialkoxysilane in which the alkoxy groups contain between one and five carbon atoms, said organopolysiloxane being prepared by heating said silane and water in the presence of a hydrolysis catalyst for about 1 to about 10 hours at a temperature between ambient and reflux to produce a siloxane partial condensation product, concentrating the partial condensation product by heating to remove about 50 to 90 mole percent alkanol byproduct and some water, precuring the concentrated product at a temperature between about 70* and 250* C. and below the gel point thereof to provide said solvent-soluble, further-curable organopolysiloxane, and C. evaporating the solvent for said organopolysiloxane and finally curing said organopolysiloxane to provide a thermoset coating on said polycarbonate surface.
 13. The process as defined in claim 12 wherein step A comprises forming a film of gamma-aminopropyltriethoxysilane on said polycarbonate surface.
 14. The process as defined in claim 13 wherein said solvent-soluble, further-curable organopolysiloxane is a hydrolysis and condensation product of a mixture of methyltriethoxysilane and phenyltriethoxysilane. 